1. Field of the Invention
The present invention relates to woven fabric that has been treated for water or stain repellency, and in particular, to hems, edges, patches and seams for such fabrics, and to methods of making the same.
2. Description of the Related Art
State-of-the-art woven fabrics used for outdoor clothing and other articles are commonly treated to make the fabric water and/or stain repellent (collectively referred to herein as xe2x80x9cwater repellentxe2x80x9d). For example, some fabrics are impregnated with a silicone resin. Water repellent woven fabrics have clear advantages. At the same time, however, fabrics treated for water repellency have a number of disadvantages. Most notably, water repellent finishes, while advantageously repelling water, also repel liquid adhesives, whether they be liquid at ambient temperature or melted at elevated temperatures. As a result, it has become an important challenge in the outdoor fabric industry to find a means for affixing patches, seam-sealing tapes and other materials to the external surface of water repellent woven fabric.
Water repellent articles generally fall into two categories: articles having a waterproof external layer, and articles having a vapor permeable membrane covered with a woven, water repellent fabric. The first group, which generally comprises rain slickers, ponchos and similar articles, uses a monolithic external layer, such as PVC, which is inherently waterproof. Because the outer layer is monolithic in nature and because the material can typically be welded, as opposed to sewn, such articles can be truly waterproof. For the same reasons, however, such articles can be heavy and can become stiff in cold weather. In addition, such articles do not allow water vapor to escape from within the article, and thus can cause discomfort due to internal condensation.
The second group of articles, such as the now famous GORE-TEX fabric, combines a waterproof but breathable internal membrane with a water repellent external woven fabric. The internal membrane allows water vapor to pass through, such as when an individual is exercising in a jacket and the moisture content inside the jacket increases. Water vapor exits through the membrane to reduce or prevent condensation on the inside of the jacket, which can maintain the individual drier and warmer. The external layer of woven fabric protects the internal layer from physical damage and helps prevent the membrane from being saturated. If the exterior surface of the membrane is saturated with water, the water itself inhibits vapor from passing through the membrane. Accordingly, it can be very important to keep the external surface of the membrane dry. Thus, the external, water repellent fabric helps prevent water from passing therethrough and being trapped against the membrane. In addition, the woven fabric resists tearing, such as when a branch or other article rubs across the material. In combination, the layers of fabric resist abrasion damage and prevent water from passing into the article, while at the same time allowing water vapor to exit the article.
Because the industry has failed to develop an adhesive that can bond with the exterior surface of water repellent woven fabrics and provide a strong, soft, lightweight and durable bond to a wide variety of textiles, all of the articles in this second group have generally required stitching, such as at the edges of the fabric, at the seams, where zippers or other articles attach to the fabric, or at the pockets. But more importantly, to prevent fraying at the edges of such fabric, the industry typically folds the edge over itself and stitches the fold. Stitching can create numerous leaks in an otherwise waterproof article, each hole allowing water to migrate through all layers of the material. Even where adhesives have been used, such as that illustrated in U.S. Pat. No. 4,604,152 to Liukko, it has still been necessary to stitch the edge of the fabric to prevent fraying. In the few cases when raw edges have been left present, a strong fraying potential remains that severely limits choices of fabrics or the cosmetically acceptable life of the garment.
To solve problems associated with stitching, the industry has developed tapes for application to the interior of the seams. The use of interior seam-sealing tape can be tedious and expensive, however, as the type of tape and adhesive must be carefully matched with the particular interior surface material, and the time, temperature and pressure associated with applying such tapes must be carefully controlled. In addition, such multi-layered, taped seams in conjunction with the turned back seam allowance add significant weight, stiffness, and cost to the resultant article. As many of these articles are used for athletic and competitive outdoor purposes, an increase in the weight and stiffness of the article is undesirable.
In addition, because the weight and bulk of such articles continue to be reduced for functionality purposes, such articles with reduced amounts of surface fiber in their top layers now are even more susceptible to damage from abrasion or other wear.
The present invention is directed toward woven fabric that has been treated with water repellent and/or stain repellent chemicals, and that is covered at least in part by a laminate patch. The laminate patch has a bottom portion in contact with the outer, treated layer of the woven fabric. The bottom portion has an adhesive system with an adhesive having a low melt point and a high flow rate and that penetrates and surrounds the fibers in the woven fiber of the outer layer of the material. The bottom portion can also contain a primer/adhesive combination for further penetration and greater bonding strength.
The patch can be shaped to cover an edge portion of the material, such as a hem or pocket flap, where there often exists a need to prevent fraying and/or delamination. The patch can also be shaped and positioned to cover a portion of the woven material that is subject to substantial abrasion, such as the elbow of a jacket.
The bottom portion of the laminate patch penetrates and surrounds the fibers of the woven material, bonding the laminate patch to the material and preventing delamination of the patch from the material and/or fraying of the material. In addition, the patch may provide additional abrasion resistance to that area of the material. The laminate strip has a top layer that is a thin, elastic, highly abrasion resistant material. In particular embodiments of the invention, other structures, such as hook and/or loop patches can be bonded onto the upper portion of the laminate patch, as the laminate patch has not been treated in the same manner as the woven material and thus the outer patch can stick to the laminate patch with traditional adhesives.
Another embodiment of the invention is directed toward stitchless seams for water repellant woven fabric, and toward methods for making the same. The fabric has an exterior layer of woven fabric that has been treated with water repellent and/or stain repellent chemicals, and an inner layer comprising a polymer membrane, such as polyurethane.
In one particular embodiment, a lapped seam is formed with a top material at least partially overlapping a bottom material, and a laminate strip positioned between the overlapping portions of the materials. The top and bottom materials are both oriented with their exterior layers facing in the same direction. The laminate strip has a bottom portion in contact with the outer layer of the bottom material. The bottom portion has a low melt point, high flow rate adhesive that penetrates and surrounds the fibers in the woven fiber of the outer layer of the bottom piece of material. The laminate strip also has a top layer in contact with the inner layer of the top piece of material. The top layer of the laminate is a thin, elastic material with a strong bonding affinity for polyurethane. The two layers of the laminate strip bond to the adjacent layers of the overlapped material to create a strong lap seam. In particular embodiments of the invention, one or both of the laminate layers also penetrates the material sufficiently to prevent the edge of the material from delaminating and/or from fraying.
Yet another embodiment of the present invention is directed toward a seam between two pieces of woven material that have been treated with water repellent and/or stain repellent chemicals, and that is covered by a laminate patch. The seam can be bonded with a laminate patch as described above, can be sewn, or can be formed by any other means generally understood in the art. The bottom portion of the laminate patch is bonded to the water repellent woven fabric and covers any stitching in the seam to prevent water migration through the stitching holes and to prevent fraying of the edges of the material.
In still another embodiment of the present invention, an accessory such as a zipper is bonded with a laminate patch to the edge of a woven material treated with a water repellent and/or stain repellent chemical. The laminate patch can effectively prevent the edge of the material from fraying and/or delaminating, while at the same time strengthening the bond of the accessory to the edge of the material.
The present invention is also directed toward methods of manufacturing such patches, edges, and seams.